Trapping Technology Research Articles

Ribosomal Protein rpS2 Is Hypomethylated in PRMT3-deficient Mice

PRMT3 is a type I arginine methyltransferase that resides in the cytoplasm. A large proportion of this cystosolic PRMT3 is found associated with ribosomes. It is tethered to the ribosomes through its interaction with rpS2, which is also its substrate. Here we show that mouse embryos with a targeted disruption of PRMT3 are small in size but survive after birth and attain a normal size in adulthood, thus displaying Minute-like characteristics. The ribosome protein rpS2 is hypomethylated in the absence of PRMT3, demonstrating that it is a bona fide, in vivo PRMT3 substrate that cannot be modified by other PRMTs. Finally, the levels 40 S, 60 S, and 80 S monosomes and polyribosomes are unaffected by the loss of PRMT3, but there are additional as yet unidentified proteins that co-fractionate with ribosomes that are also dedicated PRMT3 substrates.

High-throughput sorting and analysis of human sperm with a ring-shaped laser trap

Sperm motility is an important concept in fertility research. To this end, single spot laser tweezers have been used to quantitatively analyze the motility of individual sperm. However, this method is limited with throughput (single sperm per spot), lacks the ability of in-situ sorting based on motility and chemotaxis, requires high laser power (hundreds of milliWatts) and can not be used to dynamically monitor changes in sperm swimming behavior under the influence of a laser beam. Here, we report a continuous 3-D ring-shaped laser trap which could be used for multi-level and high-throughput (tens to hundred sperm per ring) sperm sorting based on their motility and chemotaxis. Under a laser power of only tens of milliWatts, human sperm with low to medium velocity are slowed down, stopped, or forced to change their trajectories to swim along the ring due to the optical gradient force in the radial direction. This is the first demonstration of parallel sperm sorting based on motility with optical trapping technology. In addition, by making the sperm swimming along the circumference of the ring, the effect of laser radiation, optical force and external obstacles on sperm energetics are investigated in a more gentle and quantitative way. The application of this method could be extended to motility and bio-tropism studies of other self-propelled cells, such as algae and bacteria.

Reduction of the spherical aberration effect in high-numerical-aperture optical scanning instruments

In modern high-numerical-aperture (NA) optical scanning instruments, such as scanning microscopes, optical data storage systems, or laser trapping technology, the beam emerging from the high-NA objective focuses deeply through an interface between two media of different refractive index. Such a refractive index mismatch introduces an important amount of spherical aberration, which increases dynamically when scanning at increasing depths. This effect strongly degrades the instrument performance. Although in the past few years many different techniques have been reported to reduce the spherical aberration effect, no optimum solution has been found. Here we concentrate on a technique whose main feature is its simplicity. We refer to the use of purely absorbing beam-shaping elements, which with a minimum modification of optical architecture will allow a significant reduction of the spherical aberration effect. Specifically, we will show that an adequately designed reversed-Gaussian aperture permits the production of a focal spot whose form changes very slowly with the spherical aberration.

Discovery, cloning and heterologous expression of secreted potato proteins reveal erroneous pre-mRNA splicing in Aspergillus oryzae

A novel transposon assisted signal trapping (TAST) technology, developed to specifically select only the secreted proteins, was used to discover novel extracellular plant proteins from Solarium tuberosum infected with Phytophthora infestans. Analysis of 384 hits provided 191 P. infestans and S. tuberosum sequences of secreted proteins, with an approx. 2/3 of these originating from potato. Subsequent screening for interesting genes was carried out using bioinformatics. A selected variety of the discovered sequences are presented, including a novel S. tuberosum xyloglucan endotransglucosylase (StXTH), which was cloned and subjected to detailed heterologous expression studies in Aspergillus oryzae. RT-PCR analysis of mRNA from A. oryzae StXTH1 transformants revealed that parts of the mRNA pool had been incorrectly processed, and only weak and inconsistent indications of active protein could be detected. A high AT content of StXTH1 and the occurrence of A. oryzae intron donor, acceptor, and branch point recognition sites resulted in erroneous intron interpretation (cryptic introns) of parts of the mRNA coding sequence. This may explain the difficulties generally experienced in expressing plant genes in filamentous fungi.

Single shot positron annihilation lifetime spectroscopy

Recent developments in positron trapping technology have made possible experimentation with dense interacting positronium gases. Along with these capabilities comes a need for suitable measurement techniques, and accordingly we have developed a method to measure positronium lifetimes from a single intense burst of positrons. Our method is based on recording the anode signal from a photomultiplier with a fast oscilloscope following a short-time positron burst which allows us to measure transitory effects as well as high density positronium interactions.

Precision lifetime measurements of a single trapped ion with ultrafast laser pulses

We report precision measurements of the excited state lifetime of the $5p$ $^{2}P_{1∕2}$ and $5p$ $^{2}P_{3∕2}$ levels of a single trapped ${\mathrm{Cd}}^{+}$ ion. Combining ion trap and ultrafast laser technologies, the ion is excited with picosecond laser pulses from a mode-locked laser and the distribution of arrival times of spontaneously emitted photons is recorded. The resulting lifetimes are $3.148\ifmmode\pm\else\textpm\fi{}0.011\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$ and $2.647\ifmmode\pm\else\textpm\fi{}0.010\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$ for $^{2}P_{1∕2}$ and $^{2}P_{3∕2}$ respectively. With a total uncertainty of under 0.4%, these are among the most precise measurements of any atomic state lifetimes to date.

Kinesin-driven sorting machine on large-scale microtubule arrays

Kinesin molecules can be regarded as engines (linear motors) that utilize the chemical energy of the biofuel adenosine triphosphate (ATP) to move in nanometer-precise steps along proteinaceous microtubule rails. In cell-free environments, cargoes made from different materials, including gold, silicon, glass, carbon, and polystyrene were shown to be transported by the kinesin motor along microtubules. In a previous paper, we demonstrated that the directional control of this transport can be realized using arrays of parallel and isopolar microtubules prepared by a flow field technique. The presented paper describes conditions to achieve a continuous transport of kinesin-loaded cargoes over hundreds of micrometers. These conditions include the usage of arrays in which the microtubules were immobilized at densities which make sure that the maximal lateral and longitudinal distances do not exceed the dimensions of the cargo. Additionally, each cargo to be transported had to be loaded with significantly more than one kinesin molecule. Basing on the application of laser tweezers, an approach is presented by which kinesin-driven cargoes can be transferred from one microtubule rail to a preselected other one. Corresponding to the orientation of the new rail, specified cargoes can be delivered to a predefined destination. The combination of laser trapping technologies with kinesin-driven cargo transport on highly ordered microtubule arrays might contribute to construct motor protein-based devices able to sort particles as well as single molecules.

Ion manipulation and precision measurements at JYFLTRAP

Various ion manipulation tools based on ion trapping technologies have been implemented at the IGISOL-facility in JYFL. An RFQ ion cooler and buncher is used to enhance the sensitivity of collinear laser spectroscopy and as an injector to the Penning trap. Penning traps are utilized both in nuclear spectroscopy and for precision mass measurements, as explained in the paper. Atomic masses of neutron-rich Zr, Mo and Sr isotopes were found to be in disagreement with the Atomic-Mass Evaluation and two-neutron separation energies imply strong nuclear structure effects at the neutron number N = 60.

Study on the Nano-CMM Probe based on Laser Trapping Technology using an Optical Fiber : Fundamental Analysis of the Optical Fiber Trapping(Nano/micro measurement and intelligent instrument)

A novel three-dimensional probing technique for micro parts with high aspect ratios is proposed. In this technique, a particle trapped optically at the optical fiber tip is used as a probe for position detection. Numerical analysis about the optical force and detection signal were demonstrated by using finite difference time domain method (FDTD) and Maxwell stress tensor. And also fundamental optical fiber trapping experiments were demonstrated in the water. For the first, a probe sphere was levitated by illumination from the laser, and laser light emitted from the optical fiber successfully trapped the probe sphere three-dimensionally.

Quantum Information Processing with Trapped Neutral Atoms

Quantum information can be processed using large ensembles of ultracold and trapped neutral atoms, building naturally on the techniques developed for high-precision spectroscopy and metrology. This article reviews some of the most important protocols for universal quantum logic with trapped neutrals, as well as the history and state-of-the-art of experimental work to implement these in the laboratory. Some general observations are made concerning the different strategies for qubit encoding, transport and interaction, including trade-offs between decoherence rates and the likelihood of two-qubit gate errors. These trade-offs must be addressed through further refinements of logic protocols and trapping technologies before one can undertake the design of a general-purpose neutral-atom quantum processor.

Modeling the Suppression of Sea Lamprey Populations by the Release of Sterile Males or Sterile Females

The suppressive effects of trapping adult sea lampreys, Petromyzon marinus Linnaeus, and releasing sterile males (SMRT) or females (SFRT) into a closed system were expressed in deterministic models. Suppression was modeled as a function of the proportion of the population removed by trapping, the number of sterile animals released, the reproductive rate and sex ratio of the population, and (for the SFRT) the rate of polygyny. Releasing sterile males reduced populations more quickly than did the release of sterile females. For a population in which 30% are trapped, sterile animals are initially released at ratio of 10 sterile to 1 fertile animal, 5 adult progeny are produced per fertile mating, 60% are male, and males mate with an average of 1.65 females, the initial population is reduced 87% by SMRT and 68% by SFRT in one generation. The extent of suppression achieved is most sensitive to changes in the initial sterile release ratio. Given the current status of sea lamprey populations and trapping operations in the Great Lakes, the sterile-male-release technique has the best chance for success on a lake-wide basis if implemented in Lake Michigan. The effectiveness of the sterile-female-release technique should be investigated in a controlled study. Advancing trapping technology should be a high priority in the near term, and artificial rearing of sea lampreys to the adult stage should be a high priority in the long term. The diligent pursuit of sea lamprey suppression over a period of several decades can be expected to yield great benefits.

Demonstration of conditional gate operation using superconducting charge qubits

Following the demonstration of coherent control of the quantum state of a superconducting charge qubit, a variety of qubits based on Josephson junctions have been implemented. Although such solid-state devices are not currently as advanced as microscopic qubits based on nuclear magnetic resonance and ion trap technologies, the potential scalability of the former systems--together with progress in their coherence times and read-out schemes--makes them strong candidates for the building block of a quantum computer. Recently, coherent oscillations and microwave spectroscopy of capacitively coupled superconducting qubits have been reported; the next challenging step towards quantum computation is the realization of logic gates. Here we demonstrate conditional gate operation using a pair of coupled superconducting charge qubits. Using a pulse technique, we prepare different input states and show that their amplitude can be transformed by controlled-NOT (C-NOT) gate operation, although the phase evolution during the gate operation remains to be clarified.

Trapping and marking terrestrial mammals for research: integrating ethics, performance criteria, techniques, and common sense.

We propose that researchers integrate ethics, performance criteria, techniques, and common sense when developing research trapping programs and in which members of institutional animal care and use committees address these topics when evaluating research protocols. To ask questions about ethics is in the best tradition of science, and researchers must be familiar with codes of ethics and guidelines for research published by professional societies. Researchers should always work to improve research methods and to decrease the effects on research animals, if for no other reason than to minimize the chances that the methods influence the animals' behavior in ways that affect research results. Traps used in research should meet performance criteria that address state-of-the-art trapping technology and that optimize animal welfare conditions within the context of the research. The proposal includes the following criteria for traps used in research: As Criterion I, killing-traps should render >/= 70% of animals caught irreversibly unconscious in </= 3 min (calculated with 95% confidence). As Criterion II, live-traps should trap >/= 70% of animals with </= 50 points scored for physical injury (calculated with 95% confidence). The types of traps described include killing-traps (snap traps, rotating jaw traps, snares, pitfalls, and drowning sets), common sets, and the common types of live-traps (box and cage traps, pitfalls, foothold traps. snares, corrals and nets, and dart collars). Also described are trapping methods for specific mammals, according to which traps fulfill Criteria I and II for which species, and techniques for short-term, long-term, and permanent marking of mammals.

Economic production from the artisanal fisheries of Jamaica

Economic models of production in Jamaican artisanal fisheries are explored. Cobb–Douglas and translog models of fishing effort are derived from catch and effort data for the years 1996 and 1997 to describe the relationships between catch and firm-level inputs as they vary by fishery. Data on the total catch, crew size, gear soak time and quantity of gear used yield separate functions of effort for the use of China net, trap, hand line, palanca, speargun and troll fishing technologies. By further accounting for the month and fishing location (i.e. north coast versus south coast), the seasonal and regional influences on catch rates are identified. Patterns of production include reduced catch rates associated with fishing the north coast shelf and a seasonal peak in catch levels during the late summer and fall. The use of production function models of effort is found to provide informative descriptions of fishery production processes.

Contrasting responses to object orientation and illumination by the blowflies Chrysomya chloropyga and Lucilia sericata

The alighting response of two species of blowfly, Chrysomya chloropyga (Weidemann) and Lucilia sericata (Meigen) (Diptera: Calliphoridae), were considered in relation to the orientation and illumination of a flat, oblong visual object. A strong response to orientation was displayed by L. sericata with the greatest number alighting on the vertical object; there was no significant effect of orientation on the number of C. chloropyga which alighted. Both species alighted preferentially on the more strongly illuminated side of a vertical object. With the object horizontal and more strongly illuminated from below, C. chloropyga again landed on the most brightly illuminated side. In contrast, reducing the brightness on the upper surface of the horizontally-suspended object reduced the number of L. sericata alighting on the upper surface but also reduced the overall catch, suggesting that for L. sericata the response to the illumination of a surface does not outweigh its response to its orientation. The implications of these results for the development of trapping technology for the monitoring or control of these economically important pest species is discussed.

The myosin power stroke.

Optical trapping technology now allows investigators in the motility field to measure the forces generated by single motor molecules. A handful of research groups have exploited this approach to further develop our understanding of the actin-based motor, myosin, an ATPase that is capable of converting chemical energy into mechanical work during a cyclical interaction with filamentous actin. In this regard, myosin-II from muscle is the most well-characterized myosin superfamily member. By combining the data obtained from optical trap assays with that from ensemble biochemical and mechanical assays, this review discusses the fundamental properties of the myosin-II power stroke and, perhaps more significantly, how these properties are governed by this molecule's atomic structure and the biochemical transitions that define its catalytic cycle.

Microelectrophoresis of a Bilayer-Coated Silica Bead in an Optical Trap: Application to Enzymology

We describe an apparatus that combines microelectrophoresis and laser trap technologies to monitor the activity of phosphoinositide-specific phospholipase C- δ 1 (PLC- δ) on a single bilayer-coated silica bead with a time resolution of ∼1 s. A 1- μm-diameter bead was coated with a phospholipid bilayer composed of electrically neutral phosphatidylcholine (PC) and negatively charged phosphatidylinositol 4,5-bisphosphate (2% PIP 2) and captured in a laser trap. When an AC field was applied (160 Hz, 20 V/cm), the electrophoretic force produced a displacement of the bead, Δ x, from its equilibrium position in the trap; Δ x, which was measured using a fast quadrant diode detector, is proportional to the zeta potential and thus to the number of PIP 2 molecules on the outer leaflet (initially, ∼10 5). When a solution containing PLC- δ flows past the bead, the enzyme adsorbs to the surface and hydrolyzes PIP 2 to form the neutral lipid diacylglycerol. We observed a nonexponential decay of PIP 2 on the bead with time that is consistent with a model based on the known structural properties of PLC- δ.

Mass Storage Technologies for Libraries & information Centres

To overcome growing requirements for additional space and for archival storage of less used, old and important documents, libraries have been using compact or dormitory storage and microfilming techniques. Of late, information technologies have come to their rescue. Many technologies-magnetic as well as optical have been tried for the past many years for mass storage of information. While magnetic drum and tape are,heading towards obsolescence, optical' technologies with their enormous storage capacities are trying to fill the gap. This paper overviews the various 'technologies available for mass storage in the library environment. The paper covers the magnetic storage devices including magnetic tape, magnetic disc, cartridge tape and digital audio tape. The optical disc storage technologies including read-only, write once read many and erasablelrewriteable media have been described. The role of optical discs in making electronic publishing a popular technology has also been described. Future trends in the mass storage technologies like volume holographic technology, electronic trap and proximal probe technologies, and fluorescent multi-layered technology which are under various stages of development have also been briefly discussed. Applications of these technologies in library and information centres. have been listed.

光放射圧を利用した微粒子操作によるマイクロ加工に関する基礎的研究

This paper presents a new micro-machining using a small particle controlled by optical radiation pressure induced by focused laser light, which is based on laser trapping technology. It is known that the particle of several micrometer can be trapped and moved in liquid by optical radiation pressure force, which is as small as pN to nN. It is so called laser trapping technology. In this paper, the new micro-machining are proposed, that is using small dielectric particle like a diamond grain or a silica sphere, controlled by optical radiation pressure as a machining tool. In order to verify the feasibility of new micro-machining, at first, computer simulation of trapping force are performed. The simulation results suggest that the objective with larger numerical aperture and the particles with larger refractive index are suitable for this micro-machining. Second, fundamental experiments are carried out based on the simulation results. The laser trapped diamond grain is moved at the constant path in hundreds of times on the silicon wafer surface in the machining fluid. After that, the surface to be machined is observed by using AFM. From the AFM image, it is found that the diamond grain removes the silicon wafer surface with the depth of several nanometer, even if the pressure force is as small as 0.1nN. Furthermore, it is suggested that rotating diamond grain is more efficient for micro-machining than the non-rotating diamond grain, and that even a silica sphere with smaller refractive index will be able to perform micromachining for the surface with low mechanical strength.

219 光放射圧を利用した微粒子操作によるマイクロ加工に関する研究(OS-2 機械加工(1))

This paper presents a new micro-machining using optical radiation pressure induced by incident laser light, which is based on laser trapping technology. In order to verify the feasibility of our proposed micro-machining technology, we performed the fundamental experiments based on the simulation results. As a result, we found that the proposed micro-machining will make it possible to effectively remove the surface up to the depth of several nm using the diamond grain rotated by the radiation pressure, even if the pressure force is as small as 0.1 nN.